Electric system



Aug 10, 1937. F. E. HASKELL ELECTRIC SYSTEM Filed July 16, 1952 2 SheetsSheet l ENVENTOR V Aug. 10, 1937. F. E. HASKELL 2,089,368

ELECTRIC SYSTEM Filed July 16, 1952 2 Sheets-Sheet 2 in O INVENTOR Patented Aug. 10, 1937 UNiTED STTES PATEN OFFIE 7 Claims.

This invention relates to electrical systems wherein one or more devices adapted to be operated periodically by a momentary flow of electric current are connected. to a source of electricity by controlling device, usually a makeand-break contact device, which permits a sufiicient flow of current to produce one actuation of the device being operated.

It is one of the objects of the invention to 10 conserve the current or electrical energy employed for operating such a system. This is pcculiarly feasible as the electrical energy usually employed is many times that actually required for operating the devices which receive the pcriodic impulses. This object may be stated to be to limit the electrical energy delivered to the devices to just a little more than that which is required for their operation. One resulting advantage is that more devices may be operated on simultaneously from the same source of electrical supply. It is also possible to operate the same number of devices from a source of supply otherwise too small to be satisfactory or even too small to operate the devices at all without the 05 use of the present invention.

Systems of the foregoing type usually operate during an interval of time which is much shorter than the duration of time between successive operations of the device. It is a further object O of the invention to draw electrical energy more or less continuously from the source of supply at a low rate of current flow, to store it up, and to deliver the stored-up energy quickly at a much higher rate of current flow to the device being operated. This permits smaller sources of supply to become available and also permits those types of electrical supply subject to eventual exhaustion to give suflicient operating current for a much longer life than when the larger current is drawn directly from the source.

A still further object of the invention is to reduce the wear and burning of the contacts of the make-and-break device by reducing the current therethrough to a small value before the contacts are mechanically separated and the flow of current broken.

One specific adaptation of the invention relates to electric clock systems of the type wherein a master clock adapted to keep time with a high degree of accuracy is connected electrically with a plurality of secondary clocks. Still more specifically the invention is adapted for use with those systems wherein the master clock periodically operates a contact-making device whereby impulses are transmitted to the secondary clocks and their hands are moved forward a predetermined distance which corresponds to the time interval between impulses. The source of electric current usually employed is either a primary battery, for systems having only a few secondary 5 clocks, or a storage battery, for systems having a large number of secondary clocks. When a primary battery is employed, it is usually of the dry cell type. Such a battery becomes exhausted in the course of time and it is necessary to replace it with a new one, the average life being between one and two years. The initial cost of a dry cell installation is low but this same original cost is duplicated each time a new set of batteries is installed. On the other hand, a storage battery with the charging equipment usually furnished therewith is much more expensive but does not require frequent replacement like a dry cell battery.

As already stated in a more general way, it is one of the objects of the invention to reduce the current consumption of the battery so that when a dry cell equipment is installed the life of the battery will be much longer.

It is also an object of the invention to reduce the current consumption on those systems which are usually equipped with storage batteries because the system is a little too large for economical dry cell operation and to thereby bring the system Within the range of current consumption which will permit dry cells to be used instead of storage batteries and thus save the large additional cost.

Restating an object of the invention already set forth generally, it is a specific object of the 5 invention to reduce the arcing at the make-andbreak contacts of the primary clock with the consequent burning and pitting and wearing away of the contacts. I

A still further object of the invention which has already been mentioned is to permit the battery to supply current at a very low rate for practically all of the time instead of supplying a relatively high current for a very brief interval. By using a battery in this manner it will operate 40 much longer before it finally reaches so discharged a condition that it can. no longer furnish even the small current required.

Another object of the invention is to reduce and practically eliminate the liability of injury to the battery when a short circuit occurs.

In order to more clearly explain the invention and its operation, one embodiment thereof is shown in the accompanying drawings in which buttons 22 on the arms 29 and 2|.

Fig. 1 represents a complete clock system in more or less diagrammatic form;

Fig. 2 is an elevation, partly broken away, showing in detail the escapement mechanism and contacts of the primary clock;

Fig. 3 is a plan view in detail of the primary contacts;

Fig.4 is a schematic view in elevation of one of the secondary clocks of Fig. 1; and

Fig. 5 is a schematic view in elevation of another of the secondary clocks shown in Fig. 1.

Referring to the drawings more in detail, the reference character II indicates generally a pri mary or master clock to which current is supplied by means of a battery l2. A conductor 13 connects one terminal of the battery [2 to one terminal of a high resistance l4. A conductor l5 connects the other terminal of the resistance [4 to the frame l6 of the clock H. An escapement wheel I1 is carried on a shaft l8 and is operated by means of an escapement arm l9. One or more contact arms, as indicated at 20 and 2|, may be rigidly secured to the shaft 18 and each arm carrles at its extremity a contact button 22. The escapement arm 19 is secured to a shaft 23 on which is mounted a block 24 of insulating material which in turn carries one or more contact fingers 25 and 26. Each of the contact fingers 25 and 26 carries at its extremity a contact button 21 for cooperation with one of the. contact Each contact finger and its corresponding contact arm is adapted to close the circuit through a set of secondary clocks. As shown in Fig. 1, the contact arm 25 is connected by means of a conductor 29 to one terminal of a secondary clock 29. A conductor 30 connects the other terminal of the clock 29 to one terminal of a secondary clock 3| and a conductor 32 connects the other terminal of the clock 31 to one of the terminals of a clock 33 and finally a conductor 34 connects the other terminal of the clock 33 to a terminal block 35. The other contact finger 26 is connected by means of a conductor 36 to one terminal of a secondary clock 31; a conductor 38 connects the other terminal of the clock 31 to one of the terminals of another clock 39; a conductor 40 connects the. other terminal of the clock 39 to one of the terminals of another secondary clock 4|; and by means of a conductor 42 the other terminal of the clock 4| is connected to the terminal block 35. A conductor 43 connects the terminal block 35 to one terminal of an inductance or reactance coil 44. A conductor 45 connects the other terminal of the inductance 44 to the .side of the battery '2 opposite to the side to which the conductor I3 is connected. A condenser 46 is connected between conductors l5 and 45.

The secondary clocks may be of any suitable form and are adapted to move the clock mechanism forward each time the secondary clocks receive an electrical impulse. One form of such secondary clock is shown in more or less detail in Fig. 4. A shaft 41 carries the minute hand of the clock, which minute hand is not shown in Fig. 4, and to the same shaft 41 is secured a ratchet wheel 48 adapted to receive the actuating forward impulses. A second ratchet wheel 49 with its teeth facing in the reverse direction is also secured to the shaft 41. An operating magnet 50 is connected to the terminals of the clock by suitable conductors 5| and 52 and when energized acts upon an armature 53 which is pivoted at 54 and. has pivoted at its outer end an actuating arm 55. Tension or retractile springs 56 and 51 are connected to the armature 53 and arm and pull them downwardly and to the left respectively. As is well understood in the operation of such clocks, upon operation of the magnet 50, the arm 55 is drawn upward, drops behind another tooth and upon release of the magnet 59 the spring 55, acting through the arm 55, pushes the ratchet wheel 48 forward one tooth. This carries the shaft 41 together with the minute hand of the clock in a forward direction a distance which usually corresponds to one minute of time. An arm 58 is rigidly secured to the armature 53 and cooperates with the ratchet wheel 49 to prevent the impulse received from the forward movement of the arm 55 from driving the shaft 41 and corresponding parts the far in a forward direction, that is, from over-shooting. In clock systems already installed, a non-inductive resistance 59 is commonly found to be connected across the terminals of each secondary clock in order to reduce the sparking at the make-and-break contacts of the primary clock which sparking, without such resistance, is increased by the in ductance of the magnet 59.

The secondary clock shown in Fig. 5 difiers from the secondary clock shown in Fig. 4 in that the magnet 50 and the actuating arm 55 are positicn-ed on the same side of the pivotal mounting 54 while in 4 the magnet 59 and the actuating arm 55 are positioned on opposite sides of the pivotal mounting 54. In the operation of the clock shown in 5 the pull of the magnet will positively drive the arm 55 forward while in Fig.

4 the magnet withdraws the arm and the retractile spring 55 drives the arm forward upon the release of the magnet. The clock shown in Fig. 5 also differs from the clock shown in Fig. 4 by virtue of the omission of the discharge resistance 59. The omission of this discharge resistance is not suggested as being more applicable to the arrangement shown in Fig. 5 than to the arrangement shown in Fig. 4 but as being desirable in connection with the invention disclosed herein in those systems where new clocks are being in stalled, although the present invention will operate satisfactorily with clocks already installed of the type shown in Fig. 4. The advantage of the resistance 59 in reducing sparking is less with the present invention as the sparking, as hereinafter explained, is less or none at all without such resistance. Furthermore there is also the disadvantage always present with the resistance 59 of having the working current reduced by the amount which is shunted through the path of the l clearly understood by a consideration of the discussion of the purpose. of the inductance 44 as hereinafter given.

In operation, it is common for such secondary clocks .to receive an impulse once each minute lasting, when the present invention is not employed, for an interval of time of the order of magnitude of second. In adapting the invention to an existing installation the value of the resistance 14 is so chosen that the current flowing from the battery I2 into the condenser 46 will be sufiicient to charge such condenser within the time interval existing between successive contacts of the primary clock which interval is 30 seconds as shown in Fig. l. The capacity of the condenser 46 is large enough so that when one of the contacts 25-40 or 26-2l is made, the current discharge from the condenser 46 will be sufficient in volume and duration to cause each one of the magnets in the secondary clocks of that circuit to give a complete operating impulse. The time required for such discharge to take place from the condenser through the circuit and magnets of a set of secondary clocks is very much shorter than the time interval during which the contacts remain closed, possibly of the order of 1/1000 second. It will thus be seen that while it is necessary to have the contacts in the primary clock remain closed for a relatively longer period of time in order to be certain that positive contact has been made, on the other hand, the duration of time during which the operating current completes its operating impulse is very much shorter than the time during which the contact is actually prolonged. During this very short interval of time the condenser discharges the definite and predetermined amount of current available therefrom. Thereafter no further current will flow through the operating magnets or more accurately stated only that minute current will flow which the high resistance [4 permits to flow from the battery. By thus storing up in the condenser and using only that amount of current actually required to produce the necessary impulse of the magnet instead of permitting current to flow during the entire time that the contacts are closed, it is possible to save a very large portion of such current which would otherwise be wasted.

As illustrative of the economy which may be obtained by means of the arrangement hereinbefore described, the following figures may be of interest. A certain clock system had employed dry cells of a voltage in the neighborhood of 18 volts and furnished current for A to second each time a contact was made. This was replaced by a battery of much less current capacity, that is, by a 90-volt radio B battery. The condenser used was of 100-microfarad capacity and the clocks operated in a perfectly satisfactory manner with a time interval of discharge which probably approximated 1/1000 second. The number of ohms which was used in the resistance [4 was about 200,000 and permitted sufficient current to flow so that the condenser became practically charged in 10 or 15 seconds. It will thus be seen that one of the chief advantages of the invention is a great economy in current consumption, and the possibility of greatly reducing the size or ampere-hour capacity of the battery I2 used in furnishing such current. In the actual installation just described the B-batteryof 3 ampere-hour capacity lasted longer than the ampere hour battery which had previously been used. It would also be possible to use many more clocks on the same system without increasing the ampere-hour capacity of the battery. It will be noted that the contacts 2520 and 262l are broken only after the discharge of the condenser has been completed since this discharge takes place very quickly (1/1000 second) while the contact continues for a relatively much longer time second). This means that the arcing which usually takes place at such contacts when the circuit is broken is eliminated.

A still further advantage of the invention is derived from the fact that the resistance l 4 limits the rate of current discharge from the battery l2. The initial rate at which current flows into the condenser is the maximum rate at which the battery would discharge even though the condenser or the secondary clock system were short circuited. Such an arrangement makes a very effective protection against short circuit trouble.

It would permit a battery to last for months even on dead short circuit during which time all the cir nits in trouble could be located and remedied.

he inductance 44 is inserted in the discharge circuit for the purpose of delaying somewhat the very rapid discharge of the condenser 46. It has been found in practice that it produces a more satisfactory operation of the secondary clocks as Without such inductance they would frequently tick without the hands actually being moved for ward. It is not intended to vouch for the correctness of any specific theory and why this improved operation results, but the following theories are suggested as possible reasons for this advantage. With the very high rate of current discharge taking place from the condenser 46 it is probable that the non-inductive resistance 59 takes a disproportionate amount of current as compared with the current which flows through the inductive operating magnet 50. By inserting the inductance 44 in the discharge circuit, the rate of discharge is materially reduced, and the portion of the total current which can then fiow through the magnet 50 as compared with the noninductive resistance 59 is greatly increased. Such an arrangement has been installed and is operating satisfactorily with clocks of the type shown in Fig. 4. So far as the foregoing theory is true, it would be preferable with installations where it was intended to use the foregoing arrangement to use a clock without the non-inductive resistance or such a clock as is shown in Fig. 5.

Another reason which perhaps accounts for the unsatisfactory operation without the inductance 44 is that the mechanical operation of the armature 53 and arm 55 takes place so rapidly that the end of the arm 55 does not have time to drop behind the next ratchet tooth before the current has ceased and the spring 50 has returned the arm 55 to its first position and behind the same tooth it was originally resting against. By slightly prolonging the time of the mechanical operation, the end of the arm 55 is given an opportunity to drop behind the next tooth and operate the ratchet wheel 48. As far as the theory outlined in this paragraph is concerned the arrangement shown in Fig. 5 is superior to that shown in Fig. 4 because the forward impulse of the magnet 50 is positively conveyed to the ratchet wheel 48 and there is plenty of time between impulses for the arm 55 to drop behind the next tooth.

While the description hereinbefore given refers to an electric battery as a suitable source of supply it is to be understood that the use of a very small capacity rectifier deriving its power from 'alternating current supply lines is peculiarly adapted to be combined with the energy conserving feature of the invention set forth herein either with or without the resistance l4. Such a device as well as other sources of supply are intended to be included within the meaning of the appended claims unless specifically excluded therefrom.

It is also to be understood that the foregoing embodiment of the invention has been used for purposes of illustration only and various changes may be made therein without departing from the ,spirit and scope of the invention as defined in connected at all times to said source of direct current, a high resistance connected in the circuit between said source and said condenser, and means for periodically discharging said condenser through said device 2. In an electric clock system of the impulse type, a contact-making master clock, a plurality of secondary clock circuits which each operate by a separate contact in the master clock at a definite interval of time, a condenser for supplying energy in succession to each of said circuits during the making of its contact, and means for slowly recharging said condenser during the intervals between discharges.

3. In an electric clock system, a plurality of secondary clocks, an electric circuit for supplying current to said clocks, a condenser for furnishing current to said circuit when discharging, a master clock having a. contact-making device in said circuit for momentarily connecting said condenser to said secondary clocks, a battery permanently connected to said condenser for charging it, and means between said battery and said condenser for limiting the current flowing into the condenser.

4. In an electric clock system, a plurality of secondary clocks, an electric circuit for supplying current to said clocks, a condenser for furnishing current when discharging to said circuit, a master clock having a contact-making device in said circuit for momentarily connecting said condenser to said secondary clocks, and means connected at all times to said condenser for charging it at a very minute rate of current flow.

5. In an electric clock system, a source of direct current supply, one or more secondary clocks adapted to be operated by momentary impulses of current, a pair of conductors connecting said source to said secondary clocks, a primary clock 40 having a switch connected in one of said conductors, a condenser connected across said conductors in parallel with said secondary clocks and positioned between said source and said primary clock, and means in one of said conductors posi- 5 tioned between said source of supply and said condenser for reducing the current flowing in said condenser to a value much smaller than that required for the operation of said secondary clocks.

6. In combination, a device adapted to be operated by electric impulses delivered thereto periodically, said device having the characteristic that the minimum value of current capable of causing one operation thereof will cause such operation in a period of time much less than the interval of time between operations, a condenser, a source of direct current, means for continuously charging said condenser from said source at a rate which is at all times much less than the value of current necessary to operate said device, and means for periodically discharging said condenser through said device.

7. In apparatus of the character described, an electromagnet for periodically performing some mechanical operation for which the time required after the closing of the switch which supplies current to the electromagnet is very short, conductors connecting said electromagnet to a source of direct current supply, circuit-closing means connected in the circuit of said conductors the duration of time during which said circuitclosing means is closed being much longer than the time required for the operation of the electromagnet, means for alternately closing said circuit-closing means and then opening said circuitclosing means for an interval of time many times longer than the interval of time during which it is closed, a condenser across said conductors, and a high resistance connected in series with the conductors whereby current is drawn from the source of supply to charge the condenser throughout a substantial portion of the time during which said circuit-closing means is open and. whereby the discharge current from the condenser to the electromagnet is expended at approximately the same time that the mechanical operation performed by said electromagnet is completed and much sooner than the opening of the circuit-closing means.

FRANK E. HASKELL. 

